All topical anesthetics have which type of chemical linkage?

Topical anesthetics primarily belong to the category of local anesthetics, which can be classified based on their chemical structure into amides and esters. The answer that indicates that all topical anesthetics have ester linkages is incorrect because many commonly used topical anesthetics, such as lidocaine, are amide-based.

Esters, on the other hand, are associated with many of the older local anesthetics, such as benzocaine and procaine, which are indeed topical anesthetics. However, stating that all topical anesthetics have ester linkages does not account for those that are classified as amides. The distinction is important because the metabolism, toxicity profiles, and potential allergic reactions associated with these classes differ significantly.

In summary, while some topical anesthetics are esters, not all are. The correct classification should recognize that a variety of structures exist in topical anesthetics, which includes both esters and amides, making it necessary to specify that not all topical anesthetics fall exclusively under one category. The answer would be more accurate if it acknowledged the presence of both types rather than implying universality for esters.